Navigation system for automotive vehicle with automatic navigation start and navigation end point search and automatic route selection

A navigation system for an automotive vehicle comprising:

• a map memory storing a road map which is divided into a plurality of pages further subdivided into contiguous blocks, said map memory also storing identification data for the blocks and index data for various points within the map blocks, which index data includes position data for a plurality of known points;
• an input unit for entry of the identification data for a map memory block and the index data for known points;
• a display unit for displaying on a display screen a map block based on said identification data;
• a processor accepting entry of the index data for a travel starting point and a destination through the input unit, searching for the map blocks containing the designated known points based on said entered data, said processor progressively expanding the search area along a vector between the travel starting point and the destination, said processor finding the known point closest to the travel starting point and the other known point closest to the destination along the vector and storing these known points as the navigation start point and the navigation end point, and said processor further determining a route between said navigation start point and said navigation end point.

A process for navigation of a vehicle along a preset route comprising the steps of:

• providing a road map which is divided into a plurality of map blocks and including data for a plurality of known points on a map;
• providing input data defining a start point and a destination;
• displaying said road map on a visual display screen;
• searching in a given search area for finding known points which are closest to said start point and said destination for designation as a navigation start point and a navigation end point, said given search area originally corresponding to an area of said map blocks including said start point and said destination and progressively expanding in a limited direction which is determined based on a direction between said start point and said destination;
• presetting a route between said navigation start point and said navigation end point across said map and designating known points along the preset route;
• defining a travel zone between a first starting designated known point and a second designated known point along said route;
• monitoring vehicle travel distance within said travel zone and detecting when the vehicle approaches to within a first given area of said second designated known point;
• displaying a symbol indicative of the instantaneous vehicle position through said travel zone;
• monitoring vehicle travel within said first given area for comparison with a predetermined criterion for detecting when the vehicle coincides with said second designated known point;
• shifting a vehicle position indicative symbol to said designated known point on the display;
• and
• redefining said travel zone by taking the second designated known point which currently coincides with said vehicle as said first designated known point and selecting a neighboring designated known point as said second designated known point.

A method of finding a connected path, in a feld of points of known positions, between designated start and end points, comprising the steps of storing the points of known position in a memory, and:

• (a) tesselating said field into a plurality of blocks;
• (b) sectoring said field about said start point;
• (c) identifying a target sector in which lies a straightline vector from said start point to said end point;
• (d) defining a search area, initially enclosing only the block in which said start point lies;
• (e) checking said search area for the presence of at least one of said points of known positions;
• (f) if none of said points of known position is found in step (e), expanding said search area to include blocks adjoining blocks already in said search area and lying at least in part within said target sector;
• (g) repeating steps (e) and (f) until at least one of said points is found in step (e);
• (h) defining the point found in step (a) as said start point;
• (i) repeating steps (d) through (g) in the order listed to determine said end point;
• and
• (j) electronically generating said connected path based on the start and end points found in steps (h) and (i).